Do humans understand each other? Any honest attempt to answer this question will need to consider some profound and important facts. The question is broad, but worth asking repeatedly. Modern writers and thinkers fail to fully appreciate the merit in marrying science and philosophy, which the great psychotherapists of the 20th century (and many great philosophers before them) did rather admirably. Their writings shed light on the under-explored depths of our humanity. Historically, the inevitable faults of humanness are recurrent; the whims of our finite, imperfect human nature.
Mutual misunderstandings run deep and at times prove to be dangerous. It is neither feasible nor especially useful to pass over the various reasons we fail to understand one another. There is also nothing novel or compelling about listing the countless examples of human misunderstanding such as war, tribalism, and political polarization. It is more useful to proceed with a relatively narrow focus, in an attempt to fully articulate one specific reason why humans do not truly understand one another. That reason is complexity.
In the face of the ineffable complexity of the universe—language, geopolitics, economics, the unique neurophysiology of individuals, the fundamental constituents of matter (quantum physics), and history itself—we are left to navigate oceans of uncertainty. It is therefore true that what we do not know—or cannot know—far outweighs what we do know. We are finite beings in a world of seemingly infinite complexity. It is well beyond our capacity to understand or explain even our own consciousness.